1. Field of the Invention
The present invention relates to a charged particle beam device.
2. Background Art
Usually, in a charged particle source peripheral mechanism of a charged particle beam device such as an electron gun of an electronic microscope, a distance between a cathode (negative electrode) and an anode (positive electrode) is fixed. Thus, if a low-acceleration voltage is applied in use, an electric field intensity lacks, and a sufficient electron dose can not be drawn out of the cathode. In order to improve this, as a mechanism that can vary a position of the anode, there is a related art (JP Utility Model Registration No. 1016333 (JP Utility Model Publication (Kokoku) No. 48-5947 Y (1973))) configured such that the above distance is shorten when a low-acceleration voltage is applied and a sufficient electron dose can be drawn out of the cathode by increasing the electric field intensity. Also, in JP Patent Publication (Kokai) No. 2002-8572 A, a section which can move a position of a perforated positive electrode (anode) forward and backward in an X-ray tube with respect to the negative electrode (cathode) is provided.    Patent Document 1: JP Utility Model Publication (Kokoku) No. 48-5947 Y (1973)    Patent Document 2: JP Patent Publication (Kokai) No. 2002-8572 A